Remove any tree leaves covering the rhizomes. Remove any old Iris leaves. You want your Iris beds to be clean a free from any debris. Sprinkle Preen on the beds, or any other pre-emergent, to prevent weeds. I use Preen with plant food. Some people here add alfalfa pellets to the perimeter of their Iris beds, to add nitrogen to the soil. I'm trying that this year for the first time.
Nothing more is required, unless you had problems last season -- then now is a good time to address them, such as fungal leaf-spot, borers, etc.
